Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is a highly spectral efficient technology used to transmit high-speed data through radio channels with fast fading, both in frequency and in time. Multiple-Input-Multiple-Output (MIMO) technology has become important in the wireless communication community due to its excellent characteristics. MIMO technology offers significant improvements either through Spatial Multiplexing (SM) mode, or diversity mode. With SM mode, the capacity of the communication channels grow linearly with respect to the number of supported parallel data streams. However the maximum potential of MIMO technology will only be realized in rich scattering conditions.
MIMO has always been proposed together with another important wireless technology referred to as the Orthogonal Frequency Division Multiplexing (OFDM). This multi-carrier technology is essentially a Frequency Division Multiplexing (FDM) scheme. However, contrary to ordinary FDM, the OFDM approach employs a number of closely spaced orthogonal sub-carriers to carry information data. Each sub-carrier is modulated with a conventional modulation scheme at a low symbol rate, hence maintaining total data rates similar to the conventional single carrier modulation schemes in the same bandwidth. OFDM is effective in combating the dispersion effect due to multipath propagation channel which leads to a relatively simple detection scheme.
In wireless communication systems that employ OFDM, a transmitter transmits data to a receiver using many sub-carriers in parallel. The frequencies of the sub-carriers are orthogonal. Transmitting the data parallel allows symbols containing the data to be of longer duration, which reduces the effect of multipath fading. The orthogonality of the frequencies allows the sub-carriers to be tightly spaced while minimizing inter-carrier interference. At the transmitter, the data is encoded, interleaved, and modulated to form data symbols. Overhead information is added, including pilot symbols, and the symbols (data plus overhead) are organized into OFDM symbols. Each OFDM symbol typically uses 2n frequencies. Each symbol is allocated to represent a component of a different orthogonal frequency. An inverse Fast Fourier Transform (IFFT) is applied to the OFDM symbol to generate time samples of a signal. Cyclic extensions are added to the signal and the signal is fed through to a digital to analog converter. Finally the transmitter transmits the signal to the receiver along a channel. When the receiver receives the signal, the inverse operations are performed.
The method of using dual programmable logic devices as one of mechanism of integrated circuit that can be programmed to perform specified logic functions such as MIMO-OFDM system. Another mechanism is ASICs fabrications can similarly can be used as mentioned above. The most advantage of using programmable logic devices are fast prototyping development and re-configurable option.
Since the current architecture only implemented in the single chip/device which make it impractical to map the larger design. The inventive step is to map the architecture into multiple devices which can accommodate larger design. The synchronization mechanism between devices are also necessary to make sure the data can communicate with each other accurately.